To reduce the fuel consumption of motor vehicles and therefore the pollution they generate, the practice is known of equipping a vehicle with a micro-hybrid system, for example one with an alternator-starter, by means of which a regenerative braking mode is possible.
Also known from the inventive entity is a micro-hybrid system of the above type comprising an electrical rotating machine, a reversible alternating current-direct current converter, a supercapacitor energy storage unit and a reversible direct current-direct current voltage converter.
The supercapacitor energy storage unit is formed from a plurality of very large capacity capacitors called “supercapacitor”, “ultra-capacity” or “UCAP” by a person skilled in the art.
The electrical energy recovered by means of the electrical rotating machine is stored in the supercapacitors and is then restored for various different uses, particularly for supplying consuming devices with a floating DC voltage greater than the battery voltage.
In the light of the rated values of voltage available at present for supercapacitors, it is a known practice to assemble them in series so as to form a supercapacitor energy storage unit suitable for supporting the voltage values usually present in a regenerative braking micro-hybrid system as indicated above.
In this system, the disparities existing in the rated values of voltage and of capacity of the supercapacitors have led the designers to provide for electronic balancing circuits.
Essentially, the function of these electronic balancing circuits is to protect the supercapacitors from excessively high charging voltages capable of causing voltage breakdowns or premature ageing of the capacitive unit. Furthermore, a certain uniformity of the charging voltages of the various different supercapacitors, assisting use of the capacitive unit, is obtained due to these balancing circuits. With the introduction of balancing circuits, a technical advance has been possible in terms of reliability and life of the packs of supercapacitors.